Can there be absolutely no uncontrolled flow to achieve this credit? For example, if the required retention volume for the 95th percentile storm is 100 CF, can I oversize practices to have a storage volume of 100 CF but only capture 75% of the site within the LEED boundary? This is a situation I am running into on a historical site. I cannot add practices in certain areas within the LEED boundary.

If not, that means 100% of the area within the LEED boundary needs to drain to an LID practice for this credit no matter what percentile storm you select. For urban projects, this is pretty difficult to achieve.

Thanks in advance!

Post a reply

Petra Holoubkova

LEEDuser Basic Member

2 thumbs up

Thu, 05/13/2021 - 09:29

Hi Teresa, have found any answer on this? I have a similar case - urban project in historical site, where covering 100% of LEED boundary is simply not feasible. Therefore I wonder if there is any chance to earn points for covering at least majority of the project site with GI/LID strategies..

Teresa Lin

Senior Project Engineer

LEEDuser Basic Member

3 thumbs up

Thu, 05/13/2021 - 14:22

Hi Petra, yes according to our LEED coach 100% of the area within the LEED boundary needs to be directed to a GI/LID practice of some kind and you cannot overretain in other areas to make up for uncontrolled area within the LEED Boundary. We decided to forgo the rainwater credit as it was not feasible for our project.

Gustavo De las Heras Izquierdo

LEED Expert

LEEDuser Basic Member

169 thumbs up

Thu, 05/13/2021 - 15:06

Hi Teresa, if you want to follow Option 1 you can't have uncontrolled runoff. In Option 2 there is more flexibility and it is usually easier to fulfil the requirements.

Petra Holoubkova

LEEDuser Basic Member

2 thumbs up

Tue, 05/18/2021 - 12:21

Hi Gustavo, since you mention Option 2. - do you have an experience with documenting natural land cover conditions for projects in historical sites? Our project is in area where first settlings/developement dates back to centuries ago. So pre-developed site run off volume would seem to be like a rough guess rather than a proper calculation based on some detailed evidence..

Gustavo De las Heras Izquierdo

LEED Expert

LEEDuser Basic Member

169 thumbs up

Tue, 05/18/2021 - 15:30

Hi Petra, Yes, I have experience documenting Option 2 in many projects. You can either take a guess observing the surronding landscape or use historical satellite photos.

Teresa Lin

Senior Project Engineer

LEEDuser Basic Member

3 thumbs up

Fri, 08/13/2021 - 14:04

For option 2, do you have to manage the increase in 95th percentile storm compared to predevelopment for LEED v4.1? Or is the threshold lower for option 2 similar to option 1?

Afogreen Build

www.afogreenbuild.com

Green Building Consultant

LEEDuser Premium Member

249 thumbs up

Mon, 08/23/2021 - 09:50

Hi Teresa, LEED v4 SSc4 Rainwater Management Option 2 Natural Land Cover Condition needs you to compare the runoff volume under natural land cover conditions with the runoff volume under the post-developed conditions (95th percentile). You need to subtract the natural land cover volume from the post-developed volume. The difference is what must be managed on-site. If you want to substitute with LEED v4.1, Option 2 Natural Land Cover Condition is no longer available. To comply with LEED v4.1 SS Rainwater Management:

For all projects, you can only do the percentile of rainfall events which are the threshold have been changed to 80th (1 pt), 85th (2 pts), and 90th (3 pts). LEED v4 threshold is 95th (2 pts) and 98th (3 pts).
For the zero lot line project, the thresholds have been changed to 70th (1 pt), 75th (2 pts), and 80th (3 pts). LEED v4 threshold is 85th (3 pts).

Thanks and regards,

Add new comment

To post a comment, you need to register for a LEEDuser Basic membership (free) or login to your existing profile.

You are currently logged in under an enterprise account

FAQs about SSc4 :

Do LID Practices need to capture the entire LEED boundary?

You rely on LEEDuser. Can we rely on you?

Add new comment